Project Jeeps are just that – a project. In our case, it’s a test bed for new and innovative products that will surely put us into that category of a “project that is never really finished.” So when we heard about the new Rock Krawler Triple-Threat Long-Arm Suspension for the Jeep JK, we couldn’t resist the temptation of adding it to the long list of products to test and feature. After all, a Rock Krawler Suspension system is the pinnacle in performance products for all Jeeps and is certainly not just another Jeep JK suspension kit that promises perfect suspension geometry.

Our Project Jeep JKis turning out nicely with our new Rock Krawler Suspension.

There are now many choices in the suspension department for the Jeep JK. Most are simple “kits” that include taller springs, bolt-on brackets that address track bar angles, correct bump stop height and some new shocks. These kits are great to get a little more clearance for adding bigger tires and to satisfy the weekend wheeler’s dream of being in the back country. Other kits go one step further by offering adjustable replacement suspension links that correct geometry after lifting the Jeep to a taller stature. We like these kits because they remain 100 percent bolt on for the novice wrencher, but they still give the Jeep an extra edge on the trail by having more components that are stout enough to take a beating, as well as allowing fitment of larger tires. They don’t change geometry much so there isn’t a lot to think about after installation. Get an alignment, set your pinion angle and away you go.

Another step up would be long-arm kits that simply add longer, lower links. These are also great kits, and most long-arm suspensions on the market today utilize the long lower link setup and keep factory geometry by using short upper links. We feel that this is usually a compromise in performance but it's made for the right reasons to keep installation simple and cost effective.

Rock Krawler’s innovative axle cradle/truss allows for an entirely new suspension geometry for the rear.

So, what else is there? Rock Krawler Suspension went way outside the box when they designed the Triple-Threat System for the JK, as they came up with a product that is unlike any other on the market. They created a completely redesigned and “weld-in” suspension, transforming the front and rear factory four-link design into a three-link rear and four-link front with optional removal of a link. Sound confusing? It’s not. Rock Krawler has proven its three-link front geometry over many years now with their X-Factor Suspension. But some novices, and even some of the hard-core vets, have expressed some concern in only running three links in the front of a coil-sprung Jeep. We'll touch more on this later.

Much of this suspension must be welded on, so be sure to keep that in mind.

We installed the Triple-Threat Suspension over the course of two weekends. It is a time-consuming undertaking and needs to be bolted and welded in by competent professionals or experienced home wrechers/welders. The first order of business was the removal of all factory link brackets and part of the exhaust (exhaust modifications should be done by an experience exhaust shop). We used the agonizing method of a cut-off wheel but would recommend a torch to remove these pieces.

The next step is to prep all areas that need to be welded. We easily removed the factory paint from our chassis. However, Rock Krawler powder-coats its components during manufacturing, and this adds more time to the install by having to remove this tough material, but we love having the powder coat on our suspension pieces so there is a compromise here. Other than having to remove powder coating with our flappers, installation was very straight forward; the supplied instructions were helpful and exact, and each component keyed into its place with precision for bolting on and welding. This is one of the few suspensions that we’ve installed without running into a head-scratching problem. 

Exhaust modification is required, but this is definitley something you should have your local shop handle.

Rock Krawler chooses to design its suspension links using solid alloy steel rather than standard DOM tubing, and when you pick them up you’ll feel the difference. Many think that DOM is stronger than solid stock. This is not always the case, and we want to make sure and point this out. When all is equal, meaning the material is the same and a link uses the same outside diameter, a larger cross section will always be stronger, and this theory is proven with Rock Krawler's solid links. By using 1018 and 1020 cold-rolled steel, you achieve the most consistent and strongest material possible when designing suspension links. Throw in 2-inch OD fixed bushings and flex joints that are easily re-buildable without a press and rated for 60,000 to 65,000 + lbs. radial load with +/- 20 degrees of misalignment, and you’ve got the most bad-ass links in the industry. We know some of you engineer tech heads will want to know more specifics about strength, so we’ve included some light reading for you too.

Here are a couple examples of the most commonly used materials:

For 1.75" diameter solid material I = 1/4pirexp4 = 1/4*3.14*.875exp4 = .460

For 2.00" diameter solid material I = 1/4pirexp4 = 1/4*3.14*1.000exp4 = .785

For 2" diameter 1/4" wall tubing I = 1/4piroexp4-1/4piriexp4= 1/4*3.14*1exp4 - 1/4*3.14*.75exp4 = .537

For 2" x 2" square tubing 1/4" wall I = 1/12bohoexp3-1/12bihiexp3 = 1/12*2*2exp3-1/12*1.5*1.5exp3 = .908
Cold Rolled 1018-1020 Steel's yield strength = 76,000 pounds

2" diameter 1/4" wall low carbon DOM tubing's yield strength = 26,100 to 34,800 pounds depending on mill.

2" x 2" 1/4" wall thickness electric resistance welded low carbon tubing's yield strength = 26,100 to 34,800 pounds depending on mill.

What does all this mean? Well, it’s actually pretty simple. According to the resistance to bending equations above, anything 1.75-inch will bend easier than something 2-inch (1/4-inch wall), which will bend easier than 2 x 2-inch square tubing 1/4-inch wall. However, this is only a geometric property and does not account for what material the arms are made from. Now, when you factor in the material properties of what the arms are made from you can see that the yield strength of 1018-1020 cold-rolled steel is over twice the yield strength of the competition's material. For simplification to figure out which one is the strongest, let's assume each control arm from each company is the same length and has the same end configuration. This will simplify things. So now we can compare apples to apples and figure out which control arm can carry the largest bending load.

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The Krawler joint and link for the Triple-Threat setup.

Stress = MC/I. For now we will consider the stress level to be the yield strength of the material since any stress above the yield strength will allow the arm to bend. M since we said each arm is the same length will simply be the bending Force (F) times a constant, which we can throw out for comparison sakes. C for will have a specific value for each cross section and I will be as stated above for each material.

1.75" Solid Cold Rolled Steel
76,000 pounds = F * .875/.460 therefore F = 76,000*.460/.875 = 39954 pounds

2.00" Solid Cold Rolled Steel
76,000 pounds = F * 1.000/.785 therefore F = 76,000*785/1.000 = 59660 pounds

2" Diameter 1/4" Wall Low Carbon DOM Tubing
Let's assume the highest yield stress of 34,800 pounds
34,800 pounds = F *1/.537 therefore F = 34,800*.537/1 = 18688 pounds

2" x 2" 1/4" Wall Low Carbon ERW Tubing
let's assume the highest yield stress of 34,800 pounds
34,800 pounds = F *1/.908 therefore F = 34,800*.908/1 = 31598 pounds

Simply put, this means that 1.75-inch solid cold-rolled steel can take the highest load of any material commonly used by other manufacturers today. Our Triple Threat JK links use 2.0- inch cold-rolled steel! Care to argue the point now? We didn’t think so.

Krawler Joints are a pleasant change from the norm for us. We hate the mess and wear properties of grease in flex joints. Once the grease becomes contaminated by dirt and debris, typical flex joints tend to break down quickly and lose their poly bushings. The Krawler Joints have very tight tolerances, which require the use of 3-in-1 oil to lube them instead of grease. No zirk fittings, no mess. You can also adjust the preload on each joint when assembling them, which keeps the dirt out and provides a squeak- and vibration-free ride. Amazing! Rock Krawler links are then drilled and tapped, rather than using a bung welded in, to accept the 1” shanks on the Krawler Joint. This is a much stronger method due to simplicity. Krawler Joints are tough to beat! 

So … why three links? Why four? Rock Krawler’s three-link design is simple: How many points does it take to constrain a plane? The answer is three. Any more than three mounting points on a suspension and you’ll experience bind, leading to a harsher ride and limited suspension articulation. We were able to put this theory to the test, as we can easily install or remove the fourth upper link in the Triple Threat system to get a feel for the difference. We noticed a very, very slight increase in ride quality with the front three-link setup on the road.

Handling is exceptional with the Rock Krawler long-arm system.

The Jeep handles more like a firm version of a stock Rubicon, with the three-link or the four-link in front. We’ve never felt more on-road stability in a lifted Jeep than with this system.  It’s something you need to experience to believe.  Cornering is crisp, predictable and shows little signs of body roll, even during excessive speed. There is absolutely no brake dive associated with suspension geometry or squat during acceleration, thanks to the adjustable rear upper link and anti-squat bracket. There are three adjustment points here to dial in anti-squat with this welded-in bracket, which vary depending on driving style and preferred terrain … yet another key element of this system that no other suspension company addresses or offers to the JK owner.

The rear three-link surprised us with its sure footedness. The rear end tracks as it should, as the Jeep's chassis leans into corners much like a racecar. Coming out of corners, with the suspension loaded on one side and unloaded on the other, there is no rear steer as we might have expected, likely due to the correct Instant Centers, the very long arms out back and our long wheel base. Very impressive for a Jeep that is lifted almost 6 inches.

With three links up front (or four), the 5.5-inch Rock Krawler Suspension handles very well on road. In fact, we’ve driven many JKs, including our own, with different aftermarket suspension systems and can confidently say it is the best we’ve experienced to date. We feel that the fourth link offered as the Triple Threat setup is merely there to inspire confidence to any naysayers of the three-link design and couldn’t find any downsides to running the fourth link at all times on road. We didn’t find anything negative about the three link front while on road either. While extremely rare, we have seen axle tubes (in an older Dana 30) twist out of the differential housings when a three-link suspension is used; therefore, this fourth link will obviously prevent any uncommon mishap such as this. We didn’t do any high-speed desert racing in our Rubicon, but we feel confident that our Triple Threat JK(with fourth upper link) could fly through the sand and even take a few “sweet jumps!”  We’ll get some “air” pictures to you soon.

Stability in on- and off-camber areas is where this suspension truly shines.

While performance was an eye-opening experience on road, we figured that the Rock Krawler reputation off road would blow us away. We were right! We started out testing the Triple Threat suspension on some difficult trails, and then we removed the fourth upper link on the same trail for comparison purposes. Of course, the rear end three link flexed very well with dialed in anti-squat. No jacking, walking, rear steer or pushing … and it was extremely controlled and predictable, which is just what you’d want from the rear of your Jeep.

The difference came in the front end.  The Triple-Threat suspension handled anything we could throw at it, however, after removing the fourth upper link for testing, we noticed something: Our front end experienced less bind, which translated into a quicker reaction during cycling of the suspension links. Ah ha! Within 10 minutes of being on the trail, we discovered the secret behind the three-link setup. Travel is predictable, controlled and reacts quickly, enabling tires to remain planted on the ground at any speed and over any terrain.

Through large ruts, the Rock Krawler suspension reacted quickly!

In addition to having no suspension bind, Rock Krawler designed their double sheer track bar mount brackets with enough height to have perfectly correct instant (roll) centers.  This keeps your Jeep level and stable on the trail and minimizes body roll on the street, which is what many suspension companies forget to address thoroughly. 

Suspension bind is also detrimental to the longevity of each end component. We have experienced premature bushing failure in the past and have witnessed it with all other suspension kits that use one fixed bushing end. By eliminating bind with three links, you can kiss all that early wear and tear goodbye. After many twisty, hardcore trails, our bushings look like the day we received them from Rock Krawler, with no tearing, cuts or sloppy wollowing out. Finally, no more replacing poly or rubber bushings! (Note:  we have no signs of bushing fatigue on our fourth upper link at this time.)

Once we had everything installed, we feel 39-inch tires will be welcome at this lift height.

The super long, front upper arm(s) that are actually longer than the lowers – combined with our high-clearance, long lowers – give our Jeep abilities that most others can only envy. We can cruise over wash boards and woops with smooth control. We have unmatched, bind-free, articulation that is only limited by extended shock length. The Rock Krawler Dual Sport coils are tuned perfectly for our big four-door JK, unloaded or stacked to the gills with equipment. The 5.5-inch lift height seems just about right but makes our 37-inch Procomp Extreme MTs look a little small. We love the extra break over angle this height provides the long Unlimited, but feel that a slightly larger tire is in order … so we’ve ordered up some 39-inch-tall radial Pitbull rubber. This should be the perfect combination!

With all these big improvements that Rock Krawler has made to Jeep suspensions, some say it is the little things that count. We also agree with this concept, and Rock Krawler has addressed all of the important little things. We managed to snap our factory drag link while climbing a waterfall that put some extra stress on our steering. Rock Krawler has a JK drag link, with flip kit, that will not leave you in the middle of the trail in need of under hood air tools and welders like us! They also offer an excellent and bullet-proof tie rod that will soon grace the front end of our Jeep very soon. 

Rock Krawler's exclusive adjustable bumpstops are one thing we really couldn't do without.

One upgrade that we could not live without is the Rock Krawler adjustable bump stops.  These weld-in components thread in and out as needed. In our case, we easily adjusted the proper length for our first testing. We mentioned moving up to a 39-inch tire. Within minutes, we can readjust our bump stops for perfect fitment of our new rubber. Best of all, these bump stops are universal and can be used with any aftermarket or stock suspension.

Function and strength at is best with the RK upper link mount.

Our Triple Threat Suspension makes use of a fourth upper link. Sure, Rock Krawler could have easily used the passenger-side factory upper control arm mount on the axle, but they chose to take it one step further to improve on strength. After removing the factory UCM, a new, solid, 1-inch-thick mount is welded to the axle tube. The mount uses a “build a ball joint” just like the one used on the differential mounting point. This new mount is the strongest you can get and we love the way it looks, too.

“Perfect?” Maybe! We hesitate to use the word perfect, but we will occasionally use it if we are very enthusiastic about a great product like this one. Rock Krawler uses the word perfect when describing its refined suspension geometry. It’s hard not to agree here:  Rock Krawler Suspension travel is controlled and almost limitless, the comfortable ride quality on- and off-road is unmatched, Instant Centers and Anti-Squat are confidence-inspiring details not unaddressed, strength and durability are second to none, it offers endless adjustability unlike any others on the market, and last but not least, excellent customer service at Rock Krawler Suspensions is just what you’d expect from a company that uses the word perfect when describing its products. Some of the most knowledgeable and helpful people in the industry reside at Rock Krawler Suspensions and are only a phone call away. What more could you want?  Ok, we’d want powder coating that came off easier, and no exhaust modifications. Ehh, two small tradeoffs for the best JK system on the market.

We are very pleased with the results of our Rock Krawler Suspension.

If you’re looking for a new suspension for your Jeep JK, take a look at the Rock Krawler Triple Threat and X-Factor Suspensions, along with their milder mid-arm kits. You’ll be really glad you did. Look for more upgrades to our suspension in upcoming installments, as we add longer shocks for more articulation, steering upgrades and possibly Rock Krawler coil-over front shocks!

Contact
Rock Krawler Suspension
518-270-9822
www.rockkrawler.com